Weixia Qing

Antidiabetic activity of silver nanoparticles from green synthesis using Lonicera japonica leaf extract

In this work we report the green synthesis of silver nanoparticles (AgNPs) using the aqueous leaf extract of Lonicera japonica. A color change from pale yellow to brown was observed during the synthesis process. Ultraviolet-visible (UV-vis) studies show an absorption band at 435 nm due to surface plasmon resonance of the AgNPs, further characterized using the average size and stability of the AgNPs, which were 53 nm and −35.6 mV as determined by a zeta sizer. The spherical, hexagonal shape and the face centered cubic crystalline structure of metallic silver were confirmed by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). The functional group of biomolecules present in the AgNPs was characterized by Fourier transform infrared spectra (FTIR). The synthesized AgNPs exhibited strong antioxidant activity. The antidiabetic ability of AgNPs was shown by the effective inhibition against carbohydrate digestive enzymes such as α-amylase and α-glucosidase with IC50 values of 54.56 and 37.86 μg mL−1, respectively. The inhibition of the kinetic mechanism was analyzed with LB and Dixon plots. AgNPs were identified to be reversible noncompetitive inhibitors and Ki values of 25.9 and 24.6 μg were found for key enzymes of diabetes (α-amylase and α-glucosidase). We conclude that the results suggest that the AgNPs were found to show remarkable potential antidiabetic activity against the key enzymes of diabetes and were found to be an appropriate nanomedicine for nanobiomedical applications.

Hydrogels generated by low-molecular-weight PEGylated luteolin and α-cyclodextrin through self-assembly for 5-fluorouracil delivery

Hydrophobic luteolin (LUT) was conjugated to the oligomeric chain of methoxypoly(ethylene glycol) (mPEG) to form novel amphiphilic mPEG1900–LUT conjugates. Then mPEG1900–LUT, by using its adjacent 3′ and 4′ hydroxyl groups, were assembled with magnetic Fe3O4 particles in an aqueous solution to form mPEG1900–LUT–Fe3O4 conjugates, which formed hybrid Fe3O4 particles. The spectral properties and micellization of the conjugates were studied. Both mPEG1900–LUT and mPEG1900–LUT–Fe3O4 conjugates were able to self-assemble into stable supramolecular hydrogels through α-cyclodextrin (α-CD) in water, and their gelation times and temperatures were determined. The hydrogels displayed typical porous structures, which are suitable for drug delivery. Therefore, 5-fluorouracil (5-FU) was loaded into the formed hydrogels to control its release in vitro. The drug release observations showed that introducing Fe3O4 particles into the hydrogel improved the sustained release effect.

Facile synthesis of mPEG-luteolin-capped silver nanoparticles with antimicrobial activity and cytotoxicity to neuroblastoma SK-N-SH cells

We firstly report a facile route for the green synthesis of mPEG-luteolin-capped silver nanoparticles (mPEG-luteolin-AgNPs) using mPEG-luteolin as both the reducer and stabilizer. The reaction was carried out in a stirred aqueous solution at 50°C without additional poisonous reagents. The prepared mPEG-luteolin-AgNPs was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), zeta potential and UV-vis (UV-vis) spectrum, respectively. The proportions of mPEG-luteolin capped silver nanoparticles is about 89.9%, and the content of silver is 6.65%. The mPEG-luteolin-AgNPs was evaluated the antimicrobial effects on Staphlococcus aureus, Extended spectrum β-Lactamases Staphlococcus aureus, Escherichia Coli and Extended spectrum β-Lactamases Escherichia Coli using drilling hole method. The results showed that both gram-positive and gram-negative bacteria were killed by the mPEG-luteolin-AgNPs at low concentration. Meanwhile, the cell viability assay demonstrated that mPEG-luteolin-AgNPs had toxic effects on human neuroblastoma SK-N-SH cells.

2-Bromo-1-(4-hydroxy­phen­yl)ethanone

There are two molecules in the asymmetric unit of the title compound, C8H7BrO2. In the crystal, they form independent chains propagating in [010] linked by O—H⋯O hydrogen bonds.

1-(5-Bromo-2-hydr­oxy-4-methoxy­phen­yl)ethanone

In the title compound, C9H9BrO3, the dihedral angle between the ethanone group and the aromatic ring is 3.6 (2)°. The molecular conformation is consolidated by an intramolecular O—H⋯O hydrogen bond. The crystal structure is stabilized by π–π interactions between the benzene rings [centroid–centroid distance = 3.588 (2) Å].

Functionalization of silver nanoparticles with mPEGylated luteolin for selective visual detection of Hg2+ in water sample

A novel colorimetric sensor based on mPEGylated luteolin-functionalized silver nanoparticles (mPEGylated luteolin-AgNPs) in an aqueous solution was prepared. The mPEGylated luteolin-AgNP solution was utilized to detect Hg2+ with high sensitivity and selectivity in the presence of other metal cations including Na+, K+, Mg2+, Zn2+, Ni2+, Mn2+, Ba2+, Pb2+, Sr2+, Ca2+, Cd2+, Al3+ and Cu2+. The solution could be induced to aggregate, and a color change from yellow-brown to colorless was observed in the presence of Hg2+. Meanwhile, the sensor was successfully used to detect Hg2+ in tap water with satisfactory recovery ranges using the standard addition method.

Characterisation of the mucilage polysaccharides from Dioscorea opposita Thunb. with enzymatic hydrolysis

The mucilage polysaccharides from Dioscorea opposita (DOMP) were extracted and treated with a single/dual enzymatic hydrolysis. The characterisation and viscosity were subsequently investigated in this study. DOMP obtained 62.52% mannose and 23.45% glucose. After single protease and trichloroacetic acid (TCA) treatments, the mannose content was significantly reduced to 3.96%, and glucose increased from 23.45% to 45.10%. Dual enzymatic hydrolysis also decreased the mannose and glucose contents to approximately 18%-35% and 7%-19%, respectively. The results suggest that enzymatic degradation could effectively remove the protein from DOMP accompanied by certain polysaccharides, especially mannose. The molecular weight, surface morphology, viscosity and particle sizes were measured. Enzymatic hydrolysis reduced molecular weight, decreased the viscosity, and increased the particle sizes, which indicates that the characterisations of DOMP samples were altered as structures changed. This study was a basic investigation into characterisation of DOMP to contribute to the processing of food by-products.

N-(4-Bromo-2-methyl­phen­yl)pivalamide

The conformation of the N—H bond in the title compound, C12H16BrNO, is syn to the ortho-methyl substituent. There are two unique molecules in the asymmetric unit. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules, forming infinite chains down [010].

5,3′-Dihydr­oxy-7,4′-dimethoxy­flavanone from Artemisia sphaerocephala Kraschen

The title compound, C17H16O6, was isolated from the Chinese Tibetan medicinal plant Artemisia sphaerocephala Kraschen. The molecular conformation is consolidated by two intramolecular O—H⋯O hydrogen bonds. A further intermolecular O—H⋯O hydrogen bond leads to chains along [010] in the crystal structure.